The invention relates to a mineral mining installation having a longwall structure, such as a conveyor or winning installation, and a roof support assembly constituted by a plurality of side-by-side roof support units at least some of which are provided with hydraulic bracing rams for bracing the longwall structure longitudinally.
In known installations of this type, each bracing ram is pivotally mounted between the longwall structure and the floor sill of one of the roof support units, the rams being inclined at small acute angles to the longitudinal axis of the longwall structure. The floor sills are provided with brackets for the connection of the bracing rams.
During mining operations, it may be necessary to alter the distance between one or more of the roof support units and the longwall structure, for example to enable the roof shield or shields to be advanced as closely as possible to the face being won. This is particularly important where the face slopes. Any such change in the position of a roof unit inevitably results in a change of the angle of inclination of the associated bracing ram. This in turn results in a variation of the bracing forces applied to the longwall structure which is undesirable. In particular, the bracing force decreases as the inclination of the rams increases with an increase in the distance between the longwall structure and the roof support units. This disadvantage can be overcome by adapting the points at which the bracing rams are attached to that floor sill to the changing operating conditions. The known way of accomplishing this is to change the connecting brackets.
The object of the invention is to provide connection means for such bracing rams which enable their brackets to be positioned rapidly and easily whilst ensuring that the rams maintain their required inclination even when the associated roof support units are moved.